Yellow, magenta and cyan tri-color photographic couplers are generally included in the light-sensitive layers and the color development processing of the exposed photographic material is carried out using so-called color developing agents in order to form a color photographic image. Colored dyes are provided by a coupling reaction between the oxidation product of an aromatic primary amine and the couplers. Systems which have as high a coupling rate as possible and which have good color forming properties are preferred for forming high color densities within a limited development time. Moreover, the colored dyes should be brilliant cyan, magenta and yellow dyes with little in the way of subsidiary absorptions (side-absorptions) to provide color photographic images which have good color reproduction.
On the other hand, the color photographic image which is formed must have good storage properties under various conditions. These storage conditions include dark storage conditions where the color photographic image is affected by heat and humidity and illuminated storage conditions where there is exposure to sunlight or indoor lighting, etc., and not only changes in the color of the color image, but also yellowing of the white background are of great importance.
The couplers which function as color image forming agents play an important role here, and much work has gone into making improvements by modifying the coupler structure with a view of satisfying the requirements of color photographic materials as outlined above. Conventionally 5-pyrazolone derivatives have been used in the main for the magenta couplers which are important from the viewpoint of visual sensitivity, but the dye images formed from these couplers have an absorption not only in the green light region as intended, but also unwanted absorptions in the blue and red light regions and they cannot be said to perform satisfactorily. Furthermore, the 5-pyrazolone derivatives are liable to yellowing on exposure to light and under conditions of high humidity and they are unsatisfactory from the viewpoint of image storage properties.
The magenta couplers represented by formulae (I) and (II) shown below are excellent couplers in that they are superior with respect to the light absorbing properties of the dye image and in that there is little yellowing of the white background, but they are liable to give rise to reduced speed during development and, in particular, there is a serious practical difficulty in that this trend becomes more pronounced as the coating liquid ages during the manufacture of the photographic material and when the coated photographic material is stored for an extended period of time.
The spectral sensitivity distribution obtained by spectral sensitization is of importance from the viewpoint of color reproduction. The spectral sensitivity distribution of a film material (a photographic material for taking a photograph) is preferably such that it is able to reproduce colors with a fidelity as approaching the human visual sensitivity distribution, but the circumstances are quite different from those of film material in the case of a print material (a photographic material for print). A print material is normally exposed through the cyan, magenta and yellow color dye image of a negative or positive film material and so it must have spectral sensitivity peaks corresponding to the hues of each of the color dyes in the negative or positive material.
The absorption spectrum of the magenta dyes in a film material normally has a peak wavelength between 540 nm and 555 nm and it has long been known that the preferred spectral sensitivity peak wavelength of the green sensitive layer of a print material corresponds to this region, but with the combinations of this invention, it has been found that the speed at 500 nm of the green sensitive layer is also of great importance with respect to color reproduction.
That is to say, the magenta couplers utilized in the present invention give a very sharp hue and so the colors such as red, green, blue, etc., can be reproduced with a high brilliance but, on the other hand, the colors of the green color system have often tended to reproduce as dark colors.
As a result of thorough investigation, it has been found that this tendency of the colors of the green color system to be reproduced as dark colors has a corresponding relationship with the speed at 500 nm of the green sensitive layer.